Landfills - Construction & Demolition

Excess material waste may contain chemicals and solvents that can leak out of containers and contaminate soil and groundwater. Materials may include paints, adhesives, roofing cement, caulk, sealants, epoxy, lacquer thinners, and pesticides. Oil filters, petroleum distillates, waste oils, greases, machinery lubricants, and brake fluid from vehicles and equipment may also be discarded from construction sites and wind up in C&D landfills.

Items containing hazardous chemicals such as batteries, fluorescent bulbs, appliances, air conditioning units, smoke-detector, and exit signs can be disposed of or mixed with C&D waste. Broken devices or leaching of chemicals can contaminate soil and groundwater. Devices can include mercury (electrical switches, fluorescent light bulbs, batteries, and thermometers) and polychlorinated biphenyls (PCBs) found in lighting ballasts and the dielectric fluid in transformers. Mercury is often a constituent of gases that are emitted from landfills. Mercury contained in buried landfill waste is known to migrate vertically and be released via upward emission to the atmosphere or downward leaching to groundwater. PCBs can easily accumulate in the soil and penetrate various barriers. Exposure through inhalation, ingestion, and dermal contact is associated with many health hazards.

Many C&D wastes contain inseparable hazardous constituents from bulk items. Some examples include formaldehyde in carpets, chemically treated or coated wood and insulation, fire retardants, preservatives, and surface-coated insecticides on plywood and treated wood. These hazardous constituents can leach into groundwater and discharge into surface water, possibly harming drinking water or aquatic life. They can also be released into the air during landfill fires.

Discarded debris from demolishing older structures may have asbestos-containing materials (ACM), such as ceiling and floor tile, roofing shingles, and insulation. ACM must be disposed of at a licensed facility permitted to accept it but can end up in C&D landfills. Debris may also contain lead, found on paint from walls, woodwork, siding, and doors or in pipes and solder. Lead-contaminated debris or dust can enter soil and groundwater and reach surface waters.

Hydrogen sulfide gas emissions at landfills have often been attributed to the disposal of gypsum drywall and its anaerobic breakdown. Inhalation of hydrogen sulfide in the air affects the eyes, lungs, and nervous system. Methane gas is also generated during anaerobic digestion when bacteria break down organic material. All of these processes are exothermic (heat-generating). Hydrogen sulfide, other sulfur compounds, and methane are all flammable gases that can result in surface and underground fires at high enough concentrations.

Insufficient or no landfill liner or leachate collection and treatment system can allow contaminated leachate to enter soil and groundwater, which could migrate to drinking water. Historically, C&D landfills have not been perceived as hazardous as other landfills and have not been required to adhere to leachate collection system requirements. However, groundwater monitoring and other studies indicate leachate from C&D landfills may contain hazardous components. Contaminants typically found in surrounding groundwater include cadmium, lead, iron, manganese, chlorinated VOCs, sulfate, chromium, and arsenic.

Exposure of landfills to weather elements creates a significant risk for stormwater run-off to collect excess and leached solvents, chemicals, oils, pesticides, and heavy metals. Outdoor stockpiles of appliances and equipment can also undergo weathering and release hazardous compounds with stormwater. Improper control, containment, or pre-treatment of stormwater run-off before discharging into the sanitary or storm drainage systems can pollute soil and groundwater or discharge directly into surface waters, impacting human health and aquatic systems. Stormwater run-off may fall under state or federal regulations.